Proton Therapy (PT) is a cancer treatment technology that uses high energy protons to penetrate a patient's body and deposit energy into treatment areas such as cancerous tumors. PT leverages the Bragg peak property of charged particles, such as protons, to deposit the majority of the particle's energy in the last few millimeters of travel, as opposed to conventional radiation therapy where the majority of energy is deposited in the first few millimeters of travel—which often causes significant damage to healthy tissue.
PT systems commonly implement a rotating gantry wheel to direct a beam of protons into the patient through a proton delivery nozzle from various positions around the patient during the course of treatment. The beam of protons directed into the patient is targeted into the three-dimensional shape of the desired treatment volume to deliver the therapeutic radiation precisely to the targeted location, while sparing the surrounding healthy tissue. A proton beam with a smaller cross sectional area provides greater precision in targeting, but requires more time and rotation of the gantry wheel than using a beam with a larger cross sectional area and clinicians must replace the snout of the PT system when changing between cross sectional areas.
The characteristics of the beam can include shape, size, cross-section, intensity, energy, etc. Thus, the characteristics of the proton beam include the cross-sectional shape and size of the proton beam, as defined by the aperture in the proton delivery nozzle. Traditional apertures are supported in place by a shielded snout that directs the flow of charged particles through the aperture. To shape or trim the beam of protons, the snout may include collimators to define and limit the spread of the proton beam, degraders to limit the intensity of the beam of protons, and compensators to affect the distance from the proton delivery nozzle that the charged particles deliver the majority of their energy. To change the aperture size or the trimming and focal properties of the proton beam in traditional proton nozzles, the entire snout assembly typically needs to be replaced, in addition to the clamp assembly, which can add time to the treatments using PT due to equipment change-outs. Further, because the snout contains radiation shielding, the snout is heavy and cannot be changed out without mechanical assistance.